1. Field of the Invention
The present invention relates to a tap structure and, more particularly, to a check vacuum breaking device for a tap that can prevent polluted water and impurities from polluting a piping system and can prevent frozen water from obstructing the piping system.
2. Description of the Prior Art
A conventional tap capable of supplying water includes a check vacuum breaking device installed therein to prevent polluted water and impurities from polluting a piping system because of siphonage and to prevent water from remaining therein.
With reference to FIGS. 6-8, a conventional check vacuum breaking device for a tap comprises a check member 5, a pressing member 6 made of metal material, and a pushing member 7. The check member 5 is formed in a y-shaped tube shape. The y-shaped check member 5 includes an inflow end 51, an outflow end 52, and an air-admitting end 53. The pressing member 6 is formed in a T shape, and an upper body 61 of the pressing member 6 engages with the air-admitting end 53 of the check member 5 and includes a plurality of air holes 611 arranged around a peripheral side thereof. The pushing member 7 includes a guiding pillar 71 extending to a central opening of the pressing member 6 and an anti-leak loop 73 fitted onto a stepped segment 72 thereof. As the check member 5 is in a water flowing state, the anti-leak loop 73 of the pushing member 7 attaches on a central rim 62 of the pressing member 6 with a vacuum. With the water supply stopped, the pushing member 7 can apply gravity and air to break a vacuum attaching state between the pressing member 6 and the pushing member 7 and to engage an opening of the inflow end 51 of the check member 5, thereby preventing water from flowing backward.
However, such a conventional check vacuum breaking device still has the following disadvantages:
1. As the water supply stops, the pushing member 7 moves backward to engage the opening of the inflow end 51 of the check member 5 to stop back-flowing of the water. However, the pushing member 7 and the opening of the inflow end 51 can not be closed to obtain a check function when an object gets stuck between the pushing member 7 and the opening of the inflow end 51.
2. The pushing member 7 made of metal material causes a high production cost. However, if the pushing member 7 is made of plastic material, its weight is too light to move backward to engage the opening of the inflow end 51.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.